Grinding machine



Aug 11, 1931. c. c. $TEVEN$ GRINDING MACHINE Filed June 15, 1927 s Sheets-Shae;

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BY' 7 H15 ATTORNEY Aug. 11, 1931. c. c. STEVENS GRINDING MACHINE Filed June 15, 1927 5 Sheets-Sheet 2 igZS INVEIN T012.- CLARENCE c. STE VENS 5 Y Q S *OIQ NE Aug. 11, 1931. C. c. STEVENS GRINDING momma Filed June 15, 1927 5 Sheets-Sheet 4 INVE N TO 1Q! CLARENCE C. 5 TE v1: N5,

IkEaH HUI m H/s ATTOIQN E C. c. STEVENS GRINDING MACHINE Filed June 15, 1927 5 Sheets-Sheet 5 H /5 ATTQ/QNEY Aug. 11, 1931.

Patented Aug. 11, 1931 UNITED STATES PATENT OFFICE WEE G. STEVENS, F BRISTOL, CONNECTICUT, ASSIGNOB TO THE NEW DEPARTURE EAH'UFAGTURING COMPANY, OF BRISTOL, CONNEGTICU T, A CORPORATION OF CON- GRINDING MACHINE Application filed June 15,

This invention relates to machines and comprises all the features of novelty herein disclosed, by way of example, in connection with .an internal grin machine for cutting bores in sleeves, rings and like articles.

An object of the invention is to provide an improved grinding machine for rapidly producing work-pieces of fine finish and accurate size. Another object is to provide improved controlling mechanisms for the various instrnmentalities of an internal grinder.

Another object is to provide an improved feeler gauge or size testing mechanism for controlling the various operations incident to grinding. To these ends and to improve machines of this character generally and in detail, the invention also consists in the various matters hereinafter described and claimed.

The invention, in its broader aspects, is not necessarily limited to the particular embodiment selected for'mere illustrativepurposes in the accompanying drawings in which Figure 1 is a front elevation of a grinding machine.

Figure 2 is an end elevation.

Figure 3 is a detail view, partly in section, of parts-associated with the reversing mechanism.

Figure 4 is a front view, partly in section, of parts more particularly associated with the cross feeding mechanism.

Fig.4a is a view similar'to Fig. 4 withcertain parts drawn to a larger scale.

Figure 5 is a diagrammatic view of the piping connections showing some of the valves and fluid motors in section.

Figure 6 is a cross section of parts assoclated with the reversing valve.

Figure 7 is a diagrammatic view of electrlca] connections.

Figure 8 is a horizontal section of a portion of the work head, some parts being shown in plan.

Figure 9 is a rear elevation, partly in section. of a portion of the work head controlling means.

' Figure 10 is a vertical sectional view of the work head.

1927. Serial No. 198,956.

-machine which has ways for a reciprocating carriage 4 supporting a motor driven grind-.

ing wheel 6. The carriage 4 is reciprocated by a fluid motor arranged inside the frame, the fluid being controlled by a reversing valve 8 operated by a reversing lever 10. The

lever 10 is pivoted at 12 on the frame and carries at its upper end a pivoted lever 14 which normally lies between spaced, adjustable dogs 16 and 18 which alternately strike the lever 14 to cause'the reversal of movement of the carriage 4. The lever 1i is guided by a slot in the lever 10 and is normally pressed into a position between the dogs 16 and 18 by a spring 20 (Figure 3) but, prior to finish grinding and also upon the completion of the grinding operation, a magnet 22 in a casing 23 is energized to attract a lever -2 t and thereby slide a pin 25 against the lever 14 to swing it to a positionsuch that it will be out of the path of the dogs, either momentarily for a dressing stroke, or for a longer period to let the carriage retreat to a remote position.

During grinding, the work W is held by a chuck Whose spindle is rotatably carried by a work head housing 30 which is fed transversely of the frame 2 by ratchet feed mechanism located in a feed box 32 and controlled by a rod 34 actuated by an adjustable bolt 36 on the reciprocating carriage 4. At a predetermined time, as will appear, the ratchet feeding mechanism shifts from a coarse feed to a fine feed under control of a cam which also operates a switch to cause the magnet 22 to be momentarily energized to cause a dressing stroke of the grinding wheel past a diamond supported on the work head housing, after which the grinding wheel resumes its normal reciprocation, preferably at a slower speed, for finish grinding. The dressing stroke of the carriage causes a break in the magnet circuit to de-energize the magnet. A gauge plug in the work head (to be described) is reciprocated by a rod 38 which is actuated by the carriage at every stroke.

When the work reaches size, the gauge plug enters the work and operates a switch which again energizes the magnet 22 and also energizes a magnet 40 which operates a spring held latch 42, the latch releasing a spring pressed piston rod or valve member 44 which stops the feed entirely by moving a pawl carrying lever 46. As will appear, the rod 1 also actuates a work head control valve 48 which controls two fluid motors for actuating a number of mechanisms in sequence. One fluid motor operates'retraction mechanism to cause a reversal of the feed to back the work (and a diamond carried by the work-head) away from the grinding wheel. The retracting mechanism opens or resets the switch in the feed box The other fluid motor shuts off cooling fluid, retracts the gauge plug and resets a switch in the work head, unclutchcs and brakes the work spindle, and opens the chuck to release the work. Meanwhile the grinding wheel carriage retreats to a remote position, the carriage finally operating a shut-oil valve lever 50 to shut off the flow of fluid to its cylinder. When ready to grind a new piece of work, the operator presents the work W to the chuck and operates a hand lever 52 to restore the spring pressed piston rod 44 to latched position and to operate the valve 48. This restores the ratchet feeding mechanism to operative position ready for actuation by the carriage and causes the work to be gripped in the chuck; the brake is released, the Work spindle is clutched to its driving pulley, the gauge plug is released and advanced for operation by the carriage, the cooling fluid is turned on, and a switch is set in open position. The retraction mechanism is also restored to a position ready for operation by its fluid motor. The operator opens a valve by means of the lever 50, first pulling out a spring pressed lug by a finger piece 56 to pass the plate 58, the valve allowing flow of fluid in the main cylinder. He may also actuate the cross feed of the work- 'head by the hand wheel 60 until grinding begins or he may let the carriage actuate the ratchet mechanism to feed the work up to the wheel. WVhen the wheel dressing or diamonding operation takes place, it is desirable to have the carriage move slowly. As the carriage makes its dressing stroke to carry the wheel past a diamond 62 supported .on the work head, a cam 64 on the carriage engages a roller 66 on a vertical plunger 68 to throttle the admission of fluid to the reversing valve 8 controlling the main cylinder. As the carriage comes out on the dressing stroke the dog 16 passes the lever'14 which is swung on the reverse lever 10 by the magnet 22. As soon as the dog 16 .passes the lever 14, the magnet is de-energized bythe throwing of a main switch which is actuated by the carriage during the outward dressing stroke. Hence the lever 14 on the reverse lever 10 is immediately moved by its spring back into the path of a third dog 70 on the carriage, thereby returning the carriage to normal reciprocation for finish grinding. With this general outline of principal functions, the machine will now be described in greater detail.

The diagrammatic Figure 5 shows the apparatus in operating position. The work spindle is driven by a belt driven by an electric motor 82 which also operates a pump 86. Fluid is taken by the pump from a tank 88 through pipe 90 and sent to branch pipes 92 and 94. Pipe 92 leads to an intake port 96 in the reversing valve 8. Intake fluid is alternately directed by the reversing valve 11-0 $8 1% leading t0 the 11121111 1;1111- der 102 which has its piston rod 104 connected to the carriage 4. Exhaust fluid comes back to the valve through the pipes and 98, alternately," the course of the liquid being controlled by spaced pistons 106 and 108. Intake fluid goes to the space between the pistons and into either one of the pipes 98 A or 100 depending on the position of the pistons. When exhaust fluid comes from pipe 100, it goes 'into passages 110. and 112 and out through the return pipe 114. When exhaust fluid comes from pipe 98, it goes into passage 116 and out through the return ipe. The pistons 106 and 108 areoperated y a piston rod 118 and a piston 120 in a chamber 122 to which fluid is admitted through passages 124 and 126 alternately, under control of a valve. This control valve has heads 130 and 182 connected by a hollow sleeve 134, the space outside the sleeve receiving intake fluid from a branch intake pipe 136, and directing it alternately to passages 124 and 126. Exhaust fluid from passage 126 passes to the left of head 132 and to exhaust pipe 114, and exhaust fluid from passage 124 goes to the right of head 130 then through the sleeve 134 to the exhaust pipe 114. The valve is actuated by a rod 138 pivotally connected to the reversing lever 10. A hand adjusting throttle valve 140 (Figure 6) is preferably interposed between the branch intake pipe 136 and the valve tovary the speed of reciprocation of the carriage. A second throttle valve on the plunger 68 and interposed between the main intake pipe '92 and the valve 8 is operated by the cam 64 on the carriage. The valve comprises a cup shaped member 142 slidable vertically in a sleeve 144 to uncover more or less of opposite circular openings 146 out in the sleeve and leading to the intake pipe 92. The valve has a stem 148 connected to the plunger68 carrying the roller 66 which is depressed by the cam 64 when the carriage comes out on its dressing stroke. Fluid pressure tends to raise the stem. The plunger is guided in an opening 'in a bracket 152 and held from rotation by a hut independently operable is a hand operated throttle valve comprising the above mentioned sleeve 144 which is turnahle in the valve casing by a squared stem 156 which receives a wrench or handle. Turning the sleeve valve causes its circular openings to cut 03 more or less of the fluid from the intake pipe 92. The valves 140 and 142 are to control the action of the main cylinder, their joint adjustment controlling the speed and the length of stroke. The exhaust pipe 114 leads to the shut ofi valve 158 operated by lever 50 and connected to the tank by a pipe 160.

Pressure fluid from the pump goes through branch pipe 9% to the work head control valve 48 which directs the fluid into one or the other of pipes 170 and 172, exhaust fluid coming back to the valve through one of the pipes 172 and 170 and going through a pipe 174 to the tank. The work head control valve or its piston rod controls the stopping of the ratchet feed mechanism, controls a retraction cylinder and piston causing the reversal of the feed mechanism and controls the resetting of a switch, also controls another cylinder and piston for shutting off the cooling fluid, retracting the gauge plug, resetting a switch, unclutching the work spindle drive, hraln'ng the spindle and opening the chuck. It comprises spaced pistons 17% and 178 and the piston rod ii. In the running position shown, pressure fluid is directed by the pis tons into pipe 170 leading through a branch pipe or port 189 to a retraction cylinder 192 and holding a piston 194 near one end of this cylinder. The piston rod 1'96 is connected by links 198t0 an arm 200 which is shown in the position it has prior to heing rocked to cause the reversal of the ratchet cross feed and the resetting of a switch when the flow of fluid is reversed, as will appear. Pipe 170 also leads through a four way valve 202,

which is normally open, to a pipe 28% con-.

nected to one end of head control cylinder 286. Another pipe 208 connects the other end of the cylinder to the four way valve which is connected to the pipe 172 having av branch pipe or port 210, corresponding to pipe 180, hut connected to the opposite end of the retraction cylinder 192. In the operating position shown, the piston 212 in the work-head cylinder 29% is moved to such a position as to close the chuck, release the brake, engage the clutch, release the gauge plug for operation and to turn on the cooling fluid. ()ne end oi the piston rod carries a cam 214 having a cam controlling the operation of the gauge pluggthe clutch and hrake, and the other end of the rod has nuts 216 to release a lever 218 controlling the chuck and this end of the rod engages a valve stem to open a valve'controlling the cooling fluid as will appear.

comprises the housing 30 swivelled on a hase 230 having rails 232 slidahle from front to rear on ways of the main frame. A hollow spindle 23st is mounted for rotation on hall hearings26 and 238, the hearing nearest the work being larger. The inner race rings of the hearings are clamped against shoulders on the spindle by nuts 240 and 242. The outer race rings of the hearings are held in housings 244 and 2116 on standards 2&8 and 250 by suitable clamping members 252 and 25%. The spindle is driven by a belt pulley 256 loosely mounted on bushing 258 and spaced from the smaller ball hearing by a sleeve 260. The pulley has a cohed clutch face to engage a corresponding face 262 on a grooved collar 264 which is slidahly keyed to the spindle 234. The grooved collar also has an integral braking face 256 arranged to engage a corresponding internal braking face on the housing 246. A coiled spring 268 tends to move the grooved collar to clutching position and the collar is moved to braking position by a forked lever 270 pivoted at 272 in the housing and having a curved arm 2% the end of which is normally spaced from :1 lug 276 on an arm 2T8 keyed to the cross shaft 280. This provides a. certain amount of lost motion to enable the arm to withdraw the gauge plug and open a switch prior to braking as will appear. The end of the spindle 234 carries any suitable chuck herein shown as comprising a fixture 282 with a conical face to cause contraction of a split collet section 28% forming yielding jaws that grip the work The section 284 has its huh secured for axial movement to a draw bar comprising a short sleeve 286 having spaced arms 288 slidahle in opposite longitudinal openings in the spindle under control of the fluid motor as will appear.

The spindle is keyed to an independently siidahle hollow shaft 290 carrying a detachable guage plug or feeler 292 at one end. The shaft is hollow to allow admission of cooling liuid to the work through the axis of the spindle. The shaft is threaded in a coupling 294 which rotates in a hashing 296 in a movable hracket 298. The coupling 29% surrounds and rotates with respect to a pipe section 300 keyed to an arm 302 on the movable bracket 298, suitable packing and a gla nd making a tight joint for cooling liquid entering the pipe section from a flexible tube 304. The bracket 298 is guided by the rod 38 and by aparallel rod 310 slidahle in bearings in the head. The lower rod 38 is normally reciprocated under control of the carriage 1} which at every stroke engages a roller 312 on the end of the rod 38. The rod and hence the gauge plug are pushed in one direction by the carriage and returned by a coil spring 314 surrounding the rod and interposed between a collar 316 thereon and the standard 2 18. When the work engaging 13o member or feeler, herein shown as a gauge plug, enters the work, the collar 316 moves against the arm 27 8which, when actuated, presses against the collar and retracts the gauge plug from the work prior to unclutching of the spindle, the lost motion between the lug 276 and the end of the curved arm 27 4 causing the desired sequence of action. The bracket 298 has an interiorly threaded boss 320 in which a threaded sleeve 322 can be adjustably clamped by a nut 324. A. bar 326 is secured to the sleeve and slides in a bearing lug in the housing, the free end of the bar being arranged to operate a trigger lever 328 upon the entry of the gauge plug into the work. The trigger lever is pivoted at 330 and its longer arm is normally pulled down by a coil spring 332. A notch in the lever engages: a lip 334 on a switch lever 336 to hold the latter in locked, open position. When the switch lever is released, a coil spring 338 operates a switch to complete an electric circuit. The switch is an oil switch having a bridge piece 340 attached to the switch lever and extending into an oil container 342. Spaced contact members 344, which are to be electrically connected by the bridge piece 340, are attached in a fixed position in the housing and circuit wires lead to the magnet 40. This switch is set in epen pesitien b a cross pin 346 on the rod 38 when the ro is retracted to release the gauge plug.

For sliding the draw bar or sleeve having the arms 288 to operate the chuck, the following mechanism is provided. An inner race ring of a double row ball bearings 350 is seto the arms 288 by a ring nut 352 which also supports the hollow shaft 290. The outer race ring of the bearing is clamped by a nut 354 in an encircling ring 356 having front and rear arms 358 (Fig. 8) fixed to rods 360 which are slldable in openings in a plate 362 attached to the housing. Coil springs 364 interposed between the plate and adjusting nuts 366 on the rods tend to move the ring 356 in a direction to close the chuck and grip the work. The ring is positivelymoved in one direction by upper and lower links 368 pivoted to the ring 356 and to the upper and lower arms 370 of the forked lever 218 pivoted at 372 and having its free end notched to straddle the piston rod 213. The nuts 216 threaded on the piston rod 213 are normally spaced from the end of the lever 218 but, when the piston rod moves enough, they actuate the lever. This lost motion provides for the prior actuation of other mechanisms to be now more fully described. One of them is a valve which shuts off the flow of cooling fluid to the interior of the spindle. The flexible pipe 304 above mentioned is connected to a pipe section 380 (Fig. 9) leading to a valve housing 382 which is supported in a forked bracket-384 on-the plate 362. Cooling fluid comes into '.the

valve chamber from a pipe 386. A valve 388 with a sliding stem 390 is pressed to closed position by a coil spring 392 interposed between a nut 394 on the valve stem and a guide plate 396 on the valve housing. The nut is engaged by the end of the piston rod 213 to open, and hold open, the valve but the spring closes the valve when the piston rod moves from the position indicated. The piston rod has its piston 212 working in the cylinder 206 to the ends of which fluid pres sure is alternately admitted through the pipes 204 and 208. The piston rod is extended through the end of-the cylinder and carries a cam plate 214 guided in ways on a bracket 398. The cam plate has a cam 400 arranged to engage a roller 402 on a lever 404 pivoted to a rock arm 406 fixed on the cross shaft 280. The arm is pulled by a coil spring 408 in a direction to hold the roller against the cam. A second coil spring 410 between the lever 404 and the arm 406- makes a yielding connection to compensate for inaccuracies. lVhen the piston rod and cam move towards the roller, the valve 388 for cooling fluid closes, the arm 406 and its shaft 280 are rocked to withdraw the gauge plug, reset the switch lever 336, unclutch the spindle, brake the spindle, and the lever 218 is stop screw 412 on the cylinder limits the movement of the forked lever 218 and the piston rod.

The cross feeding mechanism for the work head (see Figures 1, 2, 4 and 5) comprises a feed screw 420 actuated by the hand wheel 60 or by ratchet mechanism. 9n the feed screw, or connected to it through reduction gearing, is a ratchet wheel 422 fed step by step by a pawl 424 on the pawl carrying lever 46 which is pivoted to a swinging lever 426 pivoted to the feed box at 428'. Levers 42.6 and 46 are pulled downwardly by a spring 430 but are moved upwardly by a rock arm 432 engaging a roller 434 on the lever 426. The arm 432 is fixed to a rock shaft 436 extending under and parallel to the feed screw. The rock shafthas, at its rear end, an arm 438 carrying a roller 440 arranged in the path of a cam 442 on the rod 34 which is slidable in a casing 446' having a flange 448 bolted to the frame. The rod 34, as above stated, is moved in one direction by the bolt 36 on the carriage 4 but is moved in the other direction by a coil spring 4550 surrounding the rod and interposed between a seat on the casing 446 and a collar 452 fixed to the rod. The stroke of the rod is limited by the end face of a bushing 456 which is threaded in the casing. The outward movement of the rod 34 can be adjusted by means of the threaded bushing so that the amplitude of movement of the pawl can be varied to feed the ratchet any desired number of teeth for rough grinding. The cam 442 has A n adinctnlilg W a Hat upper face to provide lost motion to avoid overfeeding. To reduce the feed auto matically after rough grinding, the pawl is held outwardly nearer to the points of the 5 ratchet teeth so that, after a predetermined coarse feed, it will feed less teeth per stroke. A cam carrying disc 460 is frictionally held against the ratchet wheel and carries a cam 462 and a projecting lug 464 on its periphery.

19 The lug is set at such an angular distance from the cam that it will reach a stop 466 on the feed box when the cam reaches an adjustable screw or pin 468 on the pawl lever to swing the latter. The frictionally held cam carrying disc 460 is then stopped by the lug without further rotation but the ratchet continues to turn more slowly, the pawl 424 then feeding only one tooth at a stroke because it cannot swing in so far towards the ratchet. The cam 462 or a portion of it is also utilized at about this instant to complete a circuit and energize the magnet 22 near the reverse lever to cause the dressing stroke to occur. The cam pushes against a pin 469 on a bent trigger lever 470 having a notch engaging the end 472 of a switch lever 474 which is thus normally locked in open circuit position but, when the trigger lever is actuated, a spring 47 6 throws the switch lever in a direction to cause a bridge piece 478 on the lever to engage and connect two spaced contacts 480 which are in circuit with the magnet. The contact pieces are immersed in oil in a receptacle 482.

A fine feed for finish grindingcontinues until the gauge plug enters the work and actuates its switch causing the energizing of the two magnets 40 and 22. At the con clusion of grinding. it is desirable to back the work and the diamond away from the grinding wheel to provide for the subsequent free entry of the wheel into an unground work-piece. This is done by reversing-the feed screw 420. A ratchet wheel 490, with its teeth facing oppositely to the teeth on ratchet wheel 422, is fixed on the feed shaft. A pawl 492 is normally held away from this ratchet by a pm 494 fixed to the feed box and engaging a lever 496 which carries the pawl. The lever 496 is pivoted on a bell crank lever 498 swinging freely on the feed shaft 420 and having its shorter arm 500 pivotally connected by a link 502 to an arm 5&4 fastened to a hub or sleeve 506 rockable freely on the shaft- 436. The hub or sleeve 506 is rigidly secured to the arm 200 which, as ahove mentioned, is connected to and actuated by the piston in the fluid motor or retraction cylinder 192. Outward movement of the piston rod will swing the lever 498 counterclockwise and the pawl 492 will rotate the ratchet 490 and the feed screw 428 hackwardly. The final portion of the arcuate movement of the pawl lever 496 is utilized to reset the switch lever 474 in latched-open being moved entirely out of contact with its ratchet wheel at the instant that grinding is completed as will appear. The lower end of the lever 46 has a fork 514 straddling the piston rod 44 which has a collar 516 engaged by the latch 42. 'lhe latch holds the rod in a position to release the lever 46 but when the latch is released by the magnet 40, a coil spring 518 moves the rod to the right and nuts (:20 on the end of the rod engage the fork 514 and trip the pawl. When the machine is again put in operation, the hand lever 52 restores the piston rod 44 to latched position, the collar 516 camming the latch 42 into latching position where it is held by a coil spring 522. The pawl lever 46 is then free to reciprocate up and down with its pawl against the ratchet.

Referring to the diagram of electrical connections in Figure 7, a main switch is pivoted to the rear of the frame at any suitable point just below the carriage 4. The switch comprises an arm 530 and two diverging arms 532 and 534, the former being ofiset forwardly to lie in front of the latter. On the carriage 4 are two pivoted dogs 536 and 538 each tree to swing away tom the other but held by a pin 540 from swinging towards each other. The lower end of dog 536 is oilset forwardly to lie in the plane of the front arm 532 and the lower end of dog 538 lies in the planes of the rear arm 534. The switch arm 530 is arranged to connect contacts 542 and 544 or to connect contacts 546 and 548,

alternately, under control of the dogs on the carriage. The parts are shown in the relation they occupy when the machine is grinding prior to the dressing operation. A line wire 550 has electricalconnection by way of the switch arm 530 with a wire 552 leading to one of the contacts 480 and a second line wire 554 has electrical connection, by way of the magnet 22, with the other contact 480. These last contacts, as previouslydescrihed, are in the feed hos and are connected lay the bridge piece 478 under control of the feed cam. When the bridge piece is actuated by the feed cam, the magnet 22 is energized to swing the lever 14 out of the path of the dog 16 which lets the carriage come out on its dressing stroke to carry the wheel across the diamond. The magnet must he die-energized at once or the wheel would retreat to a remote position. the carriage comes out, the front or client dog 536 strikes stopping the feed and actuating switch arm 530 into a position connecting contacts 546 and 548 and disconnecting contacts 542 and 544 to de-energize the magnet 22. The third dog then causes the carriage to return to grinding position and the carriage resumes its normal stroke for finish grinding under control of the reverse lever 10 and the dogs 16 and 18. The dog 16 has its lower edge inclined to cam the lever 14 into the space between dogs 16 and 18. When the gauge plug enters the work, the bridgepiece 340 on the switch lever 336 in the work-head housing is moved to connect the contacts 344, 344. Av circuit is thus completed through both magnets 22 and 40, again tripping the lever 14 on the reverse lever, and releasing the spring pressed piston rod 44 for the fluid motors for the work head and the feed retraction. mote position, the front dog 536clears the arm 532 (which was previously placed by it in down position) and the rear dog 538 swings freely on its pivot to ride over the rear arm 534. Hence, no actuation of the main switch occurs on this long outward stroke of the carriage but the magnet 40 is de-energized when the switch in the work head is moved to open position by the gauge of the rod 560 has a cam face 564 which cams forwardly the lever 24 and pin 25 (Figure 3) in the magnet casing 23 and so locks. the lever 14. A spring 566 restores the rod 560 to un latching position when the retraction mechanism is restored by the starting mechanism to an operative position- When the carriage returns to effect grinding of a new workpiece, the rear dog 538 engages the rear arm .534 of th main switch and swings the main switch to the original position shown in Figure 7 The front dog 536 is free to swing and ride over the front arm 532.

In Figure 11, there is shown another form of work head 614 controlled by a fluid motor comprising a cylinder 616 to which fluid can be supplied through pipes 618 and 620 under control of a valve similar to the valve 48. A piston 622 is attached to a piston rod 624 passing through the ends of the cylinder and having one end guided in a sleeve 626. A grooved collar 628 on the piston rod actuates a lever 630 which has a pin or roller 632 engaging a grooved collar 634 slidable on a sleeve member 636 keyed to a hollow rotary work spindle 638. The spindle is mounted on ball bearings 637 and 639 and supports a loose pulley 640 driven by a belt 642 from a motor. The sleeve member 636 carries any suitable clutch adapted for expansion under control of a coned face 644 on the collar 634 to clutch the pulley to the spindle.

On the end of the spindle is a chuck head 648 having a face plate 650 against which a workpiece w can be clamped by a plurality of bent clamping fingers 652 pivoted on brackets 654 attached to a ring 656 slidahly keyed on an extension 657 of the chuck head. Spring pressed plungers 658 press the ring in a direction to cause the clamping fingers to swing inwardly, projections or pins 660 on the fingers engaging cam faces 662 of the chuck head or its face plate. The fingers pass through slots 664 in the chuck head and are pressed to open position by leaf springs 666 of the ring 656. Opposite the ring 656 is a .second ring 668 secured to and movable axially by pins 670 which are. guided in bearing openings 671 of the work head. Each pin- 670 is secured by an arm or projection 67 2 to a yoke. 674 for operation by the grooved collar 634. The chuck is shown in work clamping and rotating position. If the piston rod is moved to the right, the pulley is first unclutched. Next the ring 656 is frictionally engaged by the non-rotary ring 668' to cause a braking action for stopping the spindle. The ring 656 is spaced from a surface 676 on the chuck head so it can approach the latter to retract the plungers 658 and to let the clamping fingers open for release of the work-piece.

There is: $50 provision for plugging or centering av work-piece and for turning on and ofr' a supply of cooling fluid which passes through the spindle to the work. A hollow sleeve 678 extends; slidably' through the spindle and carries at one end a work engaging member comprising tapered centering plug 680. Cooling fluid is supplied to a pipe 681 secured in a bracket 682. the pipe communicating with a horizontal tube 683 which extends through the thickened end 684 of the fleeve 6'2 8 and into a bore 685 of larger diameter than the tube. The end of the tube is plugged but there is a lateral inlet port 686 normally admitting cooling fluid to the bore 685. Collars 688 are formed on the th ckened end of the sleeve 678 and have a lost motion engagement with a forked arm 689 clamped to the piston rod 624. When the piston rod moves to the right and the lost motion is taken up. during which the spindle is unclutched and braked. the thickened end 684 of the sleeve is carried over the inlet port 686 cutting off the cooling fluid from the bore 685 and the sleeve 678 slides through the spindle to cause the centering plug project through the face plate 650 into a position for receiving and centering a new work-piece. IVhen the piston rod is reversed, the work is clamped, the brake is released, the centering plug is withdrawn, the cooling fluid is turned on, and the clutch is reengaged.

Inasmuch as it is desirable to make the fln ish cut at a predetermined slow speed and to withdraw the grinding carriage at maximum 7 speed to save time at the completion of the grinding operation, the construction of throttle valve shown in Figure 12 is preferably employed. As the carriage 4 comes out on the wheel dressing stroke, the cam 64 engages aroller 700 on one arm of a bell crank lever 702 pivoted at 704 ona small casing 706 which is secured to the top of the reversing valve 8. An arm 708 is hung on the trunnion of the roller 700 and held from swinging by a stop pin 710. The arm has a shoulder 712 engaged by a lip on a latch arm 714 pivoted at 716 to a depending bent lug 718 on the rear of a head 720 which, is

pinned to the upper end of a rod 722 adjust-v ably threaded in a tapped opening on a stem 724. The stem is slidable in a turnable sleeve 726, the sleeve and the stem carrying. at their lower end, throttling instrumentalities 728 and 730 similar to the corresponding parts shown in Figure 6. The depression of the roller 700 by the cam 64 acts through the arm 708 and latch arm 714 to lower the stem 724 to throttle down the speed forwheel dressing.

The finish grinding speed is thereafter kept either at the wheel dressing speed or at some higher speed predetermined by the previous setting of nuts 7 32 threaded on the rod 722. As the stem is depressed, a latch swings over the nuts and prevents the stem from rising beyond the desired predetermined position. The latch comprises a headed stud 734- carried at the end of a latch arm 736 pivoted to the casing at 738 and pressed to latching position by a spring 740. The cam 64 keeps the stem depressed during wheel dressing, the maximum amount of throttling down depend ing on the adjustment of the rod 722 in the tapped opening of the stem 724. The increase in speed immediately following wheel dressing, as for finish grinding, depends on the position of the nuts 732 because the fluid pressure lifts the stem until' the nuts are stopped by the latch stud 734.

When the wheel carriage finally retreats to remote, position after finish grinding, no throttling down is desired but maximum speed is desired and so the throttling mechanism is rendered inoperative. The above described safety rod 560 which is actuated by the retraction cylinder 192 is arranged. at the rear of the casing 706 in a position to engage a lug 742 projecting rearwardly through a slot 744 in the casing. This trips the latch arm 714 swinging it against the tension of a spring 746 and carrying a pin 748 against the other. latch arm 7 36 and releasing it from the adjusting nuts 732, thus allowing the throttle valve to open to its greatest degree under the pressure of the fluid. Vhen the wheel carriage again comes in to grind a new piece of work, the cam 64 engages a roller 750 on another arm of the bell crank lever 702 and swings the lever against the tension of a coil spring 752 to thereby raise the hanging arm 708. The latch arm 714 then swings to latching position under influence of its spring 746.

I claim:

1. In a machine of the character described, in combination, a work-holder, means for rotating said work-holder, a tool for operating on a workpiece on the holder, a size testing member for engaging the work-piece, fluid pressure means for controlling the operation of said holder to grip the work-piece, a valve for controlling the fluid pressure means, a spring tending to operate the valve, a latch for the valve, and mechanism controlled by the size testing member for releasing the latch for causing the fluid pressure means to stop the work holder and release the workpiece; substantially as described.

2. In a grinding machine, in combination, a work holder, a grinding wheel, a reciprocating carriage for one of said members,

mechanism for causing a relative cross feed- 9 ing movement between the work holder and the grinding wheel, a reversing member controlling the reciprocation of the carriage, a size testing member for engaging a work piece on the holder, a magnet for temporarily preventing the operation of the reversing member to allow an amplified reciprocation of the carriage for wheel dressing, a switch operated by the cross feeding mechanism to cause the magnet to be energized, a switch operated by the carriage to deenergize the magnet, means for causing the work holder to grip or release the work-piece, a second magnet, and mechanism controlled by the size testing member for energizing both magnets, the second magnet controlling the actuation of the work holder for release of the work-piece; substantially as described.

3. In a grinding machine, in combination, a work holder, a grinding wheel, a work engaging member for engaging a work-piece on the holder, fluid pressure means for controlling the release of the work-piece from the holder, a valve controlling said fluid pressure means, and mechanism controlled by the work engaging member for controlling the valve; substantially as described.

4. In a grinding machine. in combination, a work holder, a grinding wheel, means for causing the holder to grip a work-piece,

a work engaging member for engaging the work-piece, a valve controlling the work gripping means, a magnet controlling the valve, and a switch controlled by the work engaging member to cause the magnet to become energized to initiate the release of the work-piece from the holder; substantially as described.

5. In a grinding machine, in combination, a work holder, a grinding wheel, mechanism for causing a relative cross feeding movement between the work holder and the grinding wheel, a work engagi member for engaging a workpiece on the holder, fluid pressure means for causing a reversal of the cross feeding movement, a valve controlling said fluid pressure means, and means controlled by the work engaging member for controlling the valve; substantially as described.

6. In a grinding machine, in combination, a work holder, a grinding wheel, means for causing a relative cross feeding movement between the work holder and the grinding wheel, a work engaging member for engaging a work-piece on the holder to control the grinding, fluid pressure means for controlling the work holder to engage and release the work and for controlling engagement of the work engaging member with the work, a valve member controlling said fluid pressure means and movable in one direction for causing said fluid pressure means to operate the holder to grip the work-piece, advancing the work engaging member to operative position and rendering the feeding means effective, said valve member being movablein another direction for causing the holder to release the work-piece, moving the work engaging member to inoperative position and stopping the feed; substantially as described.

7. In a grinding machine, in combination, a work'holder, a grinding wheel, means for causing a relative cross feeding movement between the work holder and the grinding wheel, a work engaging member for engaging a work-piece on the holder to control the grinding, fluid pressure means for controlling engagement of the work engaging member with the work, a valve member controlling said fluid pressure means and movable in one direction to advance the work engaging member to operative position and render the feeding means etl'ective, said valve member being movable in another direction to move the work engaging member to inoperative position and to stop the feed; substantially as described.

8. In a grinding machine, in combination, a work holder, a grinding wheel, a work engaging member for engaging a work-piece on the holder to control the grinding, fluid pressure means for controlling the work holder to engage and release the work and for controlling engagement of the work engaging member with the work, a valve member controlling said fluid pressure meansand movable in one direction for causing the holder to grip the work-piece and advancing the work engaging member to operative position, said valve member being movable in another direction for causing the holder to release the Work-piece and moving the Work engaging member to inoperative position; substantially as described.

9. In a grinding machine, in combination, a work holder, grinding wheel, means for causing a relative cross feeding movement between the work holder and the grinding wheel, fluid pressure means for controlling the work holder to engage and release the work, a valve member controlling said fluid pressure means and movable in one direction for causing the holder to grip the work piece and rendering the feeding means effective, said valve member being movable in another dirction "for causing the holder to release the work-piece and for stopping the feed; substantially as described.

10. In a grinding machine, in combination, a work holder, a grinding wheel, a re ciprocating carriage for one of said members,

a reversing valve controlling the reciprocation of. the carriage, means for causing an amplified reciprocation of the carriage for wheel dressing and a movement of retreat to inoperative position, a throttle valve, a cam on the carriage for actuating the throttle valve to decrease the speed of reciprocation during wheel dressing, and automatic means for preventing the cam from actuating the throttle valve during retreat of the carriage to inoperative position; substantially as described.

11. In a grinding machine, in combination, a work holder, a grinding wheel, a reciproeating carriage for one of said members, a reversing valve controlling the reciprocation of the carriage, means for causing an amplilied reciprocation of the carriage for wheel dressing and a movement of retreat to inoperative position, a throttle valve, a cam on the carriage for actuating the throttle valve to decrease the speed of reciprocation during wheel dressing, a movable member for making the cam effective to actuate the throttle valve, and, means for moving said member during the retreat of the carriage to inoperative position to prevent the cam from actuating the throttle valve; substantially as described.

12. In a grinding machine, in combination, a work holder, a grinding wheel, a reciprocating carriage for one of said members, a reversing valve cont-rolling the reciprocation of the carriage, means for causing an amplified reciprocation of the carriage for wheel dressing and a movement of retreat to inoperative position, a throttle valve, a cam on the carriage for actuating the throttle valve to decrease the speed of reciprocation during wheel dressing, a lever actuated by the cam, a movable member interposed between the lever and the throttle valve for rendering the cam eifective to actuate'the throttle valve, and means for moving said member during the retreat of the carriage to inoperative position for rendering the cam ineffective to actuate the throttle valve; substantially as described.

13. In agrinding machine, in combination, a work holder, a grinding wheel, a reciprocating carriage for one of said members, a reversing valve controlling the reciprocation of the carriage, means for causing an amplified reciprocation of the carriage for wheel dressing and a movement of retreat to inoperative position, a throttle valve, a-cam on the carriage for actuating the throttle valve to decrease the speed of reciprocation during Wheel dressing, a movable member for making the cam effective to actuate the throttle valve, a latch for temporarily holding the throttle valve from returning to wide open position, and means for moving said movablemember during retreat of the carriage to inoperative position to render the cam and the latch ineiiective; substantially as'described.

14. In a grinding machine having a reciprocating carriage with reversing dogs, a reversing member carrying a pivoted lever alternately engaged by the reversing dogs, a movable safety rod, means controlled by the size of the work being ground for moving said rod, and a cam carried by the rod'for moving and holding the pivoted lever out of reversing position substantially as described.

15. In a grinding machine having a reciprocating carriage with reversing dogs, a reversing member alternately operated by thereversing dogs, a movable safety rod, means controlled by the size of the work being ground for preventing operation of the reversing member by the dogs and for moving the safety rod, and a cam carried by the safety rod for maintaining the reversing member in non-reversing relation; substantially as described. Y

16. In a grinding machine, in combination, a work holder, a grinding wheel, mechanism including a pawl for causing a relative cross feeding movement between the work holder and the grinding wheel, fluid pressure means for controlling the operation of the Work holder to grip or release the work-piece, a valve controlling the fluid pressure means, said valve having a control rod to move the pawl of the cross feeding mechanism to inoperative position, and mechanism for actuating the valve to move the pawl of the cross feeding mechanism to inoperative position and for operating the fluid pressure means to release the work piece; substantially as described.

17. In a grinding machine, a grinding wheel, workholding means, a table or carriage carrying one of said parts, means to procure a relative cross feed between'the grinding wheel and workpiece, means to procure a limited reciprocation of said carriage, a dressing device, electromagnetic means associated with the cross feeding means adapted to extend the amplitude of reciprocation of said carriage, a gauge adapted to extend the amplitude of reciprocation of said carriage, and means for automatically shifting the control of the machine from the electromagnetic means to the gauge after the said electromagnetic means has operated.

18. In a grinding machine, a grinding wheel, workholding means, a table or carriage carrying one of said parts, means to procure a relative -cross feed between the grinding wheel and workpiece, means to procure a limited reciprocation of said carriage, a dressing device, electromagnetic means associated with the cross feeding means adapted to extend the amplitude of reciprocation of said carriage, a gauge adapted to extend the amplitude of reciprocation of said carriage, means for automatically shifting the control of the machine from the electromagnetic means to the gauge after the said electromagnetic means has operated, and means for automatically shifting the control back again to the electromagnetic means for the grinding of a subsequent workpiece.

19. In a grinding machine, a grinding wheel, workholding means, a table or carriagecarrying one of said parts, means to procure a relative cross teed between the grinding wheel and workpiece, means to procure a limited reciprocation of said carriage, a dressing device, electromagnetic means associated with the cross feeding means adapted to extend the amplitude of reciprocation of said carriage, a gauge adapted to extend the amplitude of reciprocation of said carriage, means for automatically shifting the control of the machine from the electromag netic means to the gauge after the said electromagnetic means has operated, means for automatically resetting the cross feeding means at the completion of a grinding operation for the grinding of a subsequent Workpiece, and means for automatically shifting the control back again to the electromagnetic means for the grinding of said subsequent workpiece.

20. In a grinding machine, a grinding wheel, workholding means, a rotatable member adapted to move one of said parts to procure a cross feed between the grinding wheel and workpiece, a ratchet attached to said rotatable means, a pawl and means to reciprocate it to move said ratchet wheel in one direction, a cylinder and piston unit and gearing connecting said cylinder and piston unit to the ratchet wheel and rotatable member to rotate them in the opposite direction, and fluid pressure means to actuate said cylinder and piston unit, whereby to reposition the cross feed apparatus at the end of a grinding operation.

21. In a grinding machine, a grinding wheel, workholding means, a rotatable member movement of which procures a cross feeding movement between the grinding wheel and workholding means, a pawl, means to reciprocate said pawl, a ratchet wheel adapted to be rotated in one direction by said pawl and connected to said rotatable member, a cylinder and piston unit, connections between said cylinder and piston unit and said rotatabl member, fiuid pressure means to operate said piston and cylinder unit to reposition said rotatable member by rotation in the opposite direction, and

means to hold said pawl out of engagement with the ratchet wheel during the repositioning movement aforesaid.

22. In a grinding machine, a grinding wheel, a chuck, a table or carriage carrying 0 one of said parts, a gauge adapted to engage a workpiece in said chuck by end contact therewith, means associated with said gauge to cause said carriage to separate the grinding wheel and chuck upon completion of a 5 grinding 0 eration, said means thereafter acting to ring said grinding wheel and chuck together again, and automatic means to move said gauge out of the chuck before the grinding wheel and chuck have come to- 3 gether whereby to allow a workpiece to be introduced into the machine without interference by said gauge.

In testimony whereof I hereunto afiix my signature.

CLARENCE G. STEVENS. 

